Algebra Examples

$2 \cos (\frac{2 π}{3})$

Step 1

Apply the reference angle by finding the angle with equivalent trig values in the first quadrant. Make the expression negative because cosine is negative in the second quadrant.

$2 (- \cos (\frac{π}{3}))$

Step 2

The exact value of $\cos (\frac{π}{3})$ is $\frac{1}{2}$ .

$2 (- \frac{1}{2})$

Step 3

Cancel the common factor of $2$ .

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Step 3.1

Move the leading negative in $- \frac{1}{2}$ into the numerator.

$2 (\frac{- 1}{2})$

Step 3.2

Cancel the common factor.

$2 (\frac{- 1}{2})$

Step 3.3

Rewrite the expression.

$- 1$